The present invention relates, in general, to constant volume fluid flow control devices for fluid conduits which supply fluid to a zone. In particular, the present invention relates to devices which utilize damper means for regulating fluid flow through the conduit to the zone and, specifically, relates to damper control means for regulating the damper.
Heretofore, the problem of providing a damper control in order to maintain a zone at a desired temperature has been solved by utilizing an external energy source to operate the damper control device. Exemplary of such systems is my co-pending Application for U.S. Letters Patent, Ser. No. 711,066 which utilizes compressed air from an external source or electricity to operate the damper control mechanism.
It has been found in these prior embodiments that the utilization of an external energy source is a complex, expensive approach to solving the problem of operating the damper control mechanism. Further, due to the complexity of these prior art approaches, there is a higher potential for failure of the damper control device than would be present in a more simplified system. Finally, the prior art approaches to the problem of damper control device operation which rely on an external energy source are potentially capable of providing uncontrolled fluid flow through the conduit to the zone should said external energy source fail while fluid is flowing through the conduit.